This work reports on the analysis of the near-UV and visible absorption spectrum of water vapor. Obtained by combining a high- resolution FT spectrometer and a long path White multiple- reflection cell. A large number of water vapor lines belonging to highly excited vibrational levels are identified. Most of these lines have not been observed previously and do not appear in the spectroscopic databases HITRAN and GEISA, widely used for atmospheric calculations. All identified lines are fitted with a Voigt profile using the WSPECTRA program and their cross section and self-broadening parameters at 291 K are determined. A particular attention is give to the integrate cross section over the total spectral range investigated, in order to estimate the contribution of the weak UV-visible water vapor absorption lines to the earth's radiation balance. Preliminary measurements of cross section in the 20000-16000 cm-1 spectral range are also presented.